Gallery: MSD Introduces the Atomic 2 EFI Fuel Injection (Videos)

The often-paraphrased Ralph Waldo Emerson quote states, “If a man can write a better book, preach a better sermon, or make a better mousetrap than his neighbor, though he builds his house in the woods, the world will make a beaten path to his door.” Recently, MSD introduced the Atomic 2 EFI (part no. 2910-2BK or 2910-2) fuel injection system, a better mousetrap, so MSD had better be prepared for the world to beat a path to their door (or website).

When MSD introduced the original Atomic EFI several years ago, computer technology was not as advanced as today. After years of selling the successful Atomic EFI, MSD has taken advantage of technology advancement by introducing the Atomic 2 EFI, a better product in a more compact package.

MSD’s all-new Atomic 2 EFI is ready to improve the performance and drivability of your Mopar. The Atomic 2 EFI is available in raw aluminum finish or a black ceramic option.

The Atomic 2 throttle body flows 865 CFM, features 1.75-inch throttle plates, and handles higher horsepower than the previous Atomic unit. It supports up to 650 HP naturally aspirated or 635 HP in forced induction applications.

The Atomic 2, just like the Atomic, is a direct replacement for all square bore, 4150-style 4-barrel carburetors. The MSD 2 version provides effortless startups, fine idle quality, and excellent drivability – all of which the original possessed, but the new unit has many benefits over its predecessor.

The Atomic 2 comes with four 100 lb/hr fuel injectors that can support normally aspirated engines up to 650 horsepower (hp) and forced-induction engines up to 635 hp. The original unit could only operate with a 625 hp engine while requiring a special fuel system and pump.


Top Left: The Atomic 2 is equipped with four 100 lb/hr injectors rather than the 80 lb/hr injectors of the original Atomic unit. To reduce wiring and ECU mounting complexity, the Atomic 2 has an integral ECU housed in the throttle body. Top Right: The throttle body design looks like a carburetor, but the effortless startups, outstanding idle characteristics, and impressive drivability are a trademark of what electronic fuel injection can provide. The Atomic 2 fits any 4150 four-barrel carburetor flange. All the sensors are OEM-quality components, so each sensor should provide years of trouble-free operation. Bottom Left: The MSD Atomic 2 requires only four wires to be electrically operated. Two of the cables are the battery positive and negative wires. Additionally, a 12-volt switch source and an RPM input are required. Bottom Right: Included with the Atomic 2 is a Genuine Bosch LSU 4.9 Wideband Oxygen sensor that provides real-time fuel map learning. The Oxygen sensor’s installation can be accomplished with a clamp-on Oxygen sensor or a weld-on Stainless Steel oxygen sensor bung.

The injectors are housed in an 865-cfm throttle body with four 1.75-inch throttle plates mounted on two shafts that ride on roller bearings for smooth throttle operation. The fuel is delivered via annular boosters to improve the fuel atomization to each intake runner and port. To measure the fuel pressure, the Atomic 2 comes with an integrated fuel pressure sensor.

The EFI 2 comes with a self-contained ECU integrated into the throttle body housing rather than a separate location as on the original version. There is a full-color touchscreen instead of the joystick input device found with the Atomic. Lastly, the Atomic 2 requires only four wires (battery positive, battery negative, switched 12-volt, and RPM signal) to be electrically powered.

Left: A new feature of the Atomic 2 is the touchscreen controller. The controller is used for the Atomic setup, adjusting the fuel injection parameters, and as a gauge monitoring device. Middle: Custom tuning is available with the computer-based Advanced Tuning software. The Atomic 2 can handle power adders such as turbochargers and superchargers. Right: Incorporated into the Advanced Tuning software is a fan controller for one or two electric fans. The tuner can adjust the engine idle for increased engine loads from the air conditioning compressor. The software can control a second fuel pump. If a sensor’s output falls outside of the acceptable parameters, the software can provide trouble codes.

The 3.5-inch touchscreen controller is used for initial setup, tuning, and gauge monitoring. MSD provides custom tuning with their computer-based Advanced Tuning software, so fine-tuning can be done on your laptop. The Atomic 2 can handle power adders. A fan controller is integrated into the tuning software. Up to two electric fans can be incorporated and operated through outputs from the Atomic 2.

A Genuine Bosch LSU 4.9 Wideband Oxygen sensor provides real-time fuel map learning. The Oxygen sensor can be threaded into a clamp-on Oxygen sensor kit for a weldless, leak-free installation or a weld-on Stainless Steel oxygen sensor bung; both included with the Atomic 2. The Atomic 2 EFI utilizes an OEM-style throttle position sensor, idle air control valve, and fuel pressure sensor for years of trouble-free operation. The MSD Atomic 2 has a redesigned throttle bellcrank with the proper provisions for the Mopar throttle cable and kick-down linkage.

The Atomic 2 comes with a throttle bracket that works with a Mopar throttle cable and the mechanical kick-down linkage found on the automatic shifted Torqueflites.

The Atomic 2 is compatible with MSD, Holley Hyperspark, and OEM Hall-effect and Captive Discharge (CD) ignition systems. The compatibility extends to the Holley EFI digital dashes, gauges, and fuel system components. For the fueling system, there are a few options. The fuel tank can be removed, and a Holley Retrofit EFI Fuel Pump Module can be installed depending upon the tank design.

Additionally, Holley offers fuel tanks with the in-tank fuel module installed, and the range of tanks covers many of the classic muscle car era cars and trucks. As a final option, Holley offers a pump that mounts outside of the tank at a low point parallel to the fuel tank’s bottom. An external fuel pressure regulator (part no. 12-882) is required regardless of which pump option was selected. The pressure is regulated to 58.5 psi.

For the fueling system, MSD/Holley offers a few options. A Holley Retrofit EFI Fuel Pump Module can be installed depending upon the factory tank compatibility. Holley offers fuel tanks with the in-tank fuel module installed. Check with Holley to find out if your Mopar’s tank is available. Lastly, Holley offers a pump that mounts externally from the tank.

If you are interested in stepping up from a carburetor or moving to a more efficient EFI system, the Atomic 2 EFI is for you. It provides easy setup and expanded adjustability options with the touchscreen controller. The fuel trim is learned with Oxygen sensor feedback.

The Atomic 2 has the expandability to incorporate many Holley company fuel system kits, distributors, digital dash displays, and fuel regulators. With MSD taking care of your fuel system needs, the only choice you will have to make is what exterior option you want, a black ceramic finish or raw aluminum.



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Chris Holley

Technical Contributor Chris has been a college professor for 25 years; at Pennsylvania College of Technology in Williamsport, PA. for the last 20 years. Chris instructs automotive classes in HVAC, electrical/electronics, and high-performance, including using a chassis dyno, flow benches, and various machining equipment. Recently, he added a vintage vehicle upholstery class to his teaching assignments. Chris owns a '67 Dart, a '75 Dart, a '06 Charger, and a '12 Cummins turbo diesel Ram, and he is a multi-time track champion (drag racing) with his '69 340 Dart, which he has owned for 34 years.

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